The Wright Brothers efforts at Kill Devil Hills (Kittyhawk) were destined for a time to make Man indivisible from Machine - that is no airplane could fly without a pilot. The fragile contraptions the wright Brothers flew would demolish themselves on the nearest sand dune at the slighest distraction from the task of guiding the machine. So a pilot was assumed from day one to be an essential part of the control equation.
WWI, although establishing the roles of fighters, bombers, and observation aircraft, passed without any significant change in this aim. The aircraft of WWI, celebrated though they may be, were, in a word, uncontrollable. The modern pilot expects that his aircraft, no matter how small or large, can be trimmed to maintain level flight. He also expects that a hand on the stick will produce a commensurate response: a sharp haul back, produces a quick nose up. Gentle caress to the right, slow roll thereto.
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The Kettering Bug
One of the first UAVs
Developed under the direction of Charles Kettering began at the Delco and Sperry companies in 1917. Made of wood, weighing 270 kg, (including 135-kg of explosives) it was powered by a 40-h.p. Ford engine. Using a rudimentary method of guidance that factored in wind speed, direction and target distance, the number of revolutions the engine needed to fly the target was calculated.
The Kettering Bug took off using a four-wheel carriage that ran along a portable track. Once airborne it was controlled by a small gyroscope, its altitude measured by an aneroid barometer. When the engine completed the prescribed number of revolutions, a cam dropped, causing bolts that fastened the wings to the fuselage to be pulled in. The wings then detached and the fuselage fell onto its target.
The Kettering Bug was successfully demonstrated in 1918 before Army Air Corps observers in Dayton, Ohio. However, World War I hostilities ended before the missile could be put into production.
Although crude by current standards the guidance system incorporated principles that were later used by Germany's V1 Buzz Bomb.
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Not so the WWI machines. Without exception, they required attention every instant of their flight. The Sopwith Camel's natural instability was accentuated by the inertia of the rotary engine. As it happened, the precessional effect of the crankcase and the cast iron cylinders rotating at 1500 rpm markedly assisted a pitch-up and roll to the right.
It is not widely appreciated that Alcock and Brown, who flew a Vickers Vimy across the Atlantic, only did so by virtue of leaning on the control column every second that they were airborne. Relaxing on the control column meant an uncontrollable pitch up, a stall and a watery grave in an Atlantic as hungry for aviators as it was for sailors. Lang Kidby's (a former Australian Army Aviator) replica Vimy was very carefully redesigned to allow the aircraft to be trimmed out in level flight. (see Lang's article)
The point is that Man did not know how to design aircraft in the dimensions and ratios that gave easy controllability. Controllability starts with the ability to fly straight and level at a chosen altitude, from which, one may survey the globe, and depending on one's aim, admire it or engage specific points thereof.
It was not until the mid-30's that the mathematical equations which described the behaviour of the airborne body were written. This is generally ascribed to one Walt Whitman, later an Apollo Mission Director, but at the time, a luminary of NACA, an American body intended to support and further research into Aeronautics, as it was then known. This was not a trivial exercise. In it's simplest manner, determining the behaviour of an aerodynamic body such as an aeroplane requires attention to 24 simultaneous equations, each containing three unknowns. This, of course, presumes that it has become airborne, a manoeuvre that is difficult, even now, to predict. A very expensive remotely piloted vehicle crashed on takeoff quite recently. Seems the computer was not programmed far enough one way or the other.
Until one could design a vehicle which would be controllable with a resident pilot, there was little future in unmanned vehicles. And, despite several other Whitmans around the world, WWII saw very little in the way of successful unmanned vehicles, at least, to start with. Because, to get a stable and controllable unmanned vehicle, one had to start with a stable manned vehicle. One which had a known and easily predictable response to all of the usual control movements. Mathematically, this meant that such abstruse factors as the rate of rearward movement of the control column, as well as the actual distance moved, had to produce easily understood responses ( the aircraft 's nose came up, say 10 degrees ), all in accordance with the known system of mathematical equations. This was the Allies approach.
The Germans, who won everything in WWII except the Philosophical and Logistics battles, came first here. They designed and put into operation the V-1 and V-2. These missiles were completely machine controlled from launch to landing. They did not rely upon an existing aeroplane for their control laws. They adopted a "If it's going the wrong way, then let's give it a blip the right way" guidance system philosophy.
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| The V-1 |
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Prior to launch the range and bearing to the target was calculated and set in the weapons guidance system. A tiny propeller on the nose was attached to a counter. When the pre-set number reached zero, the air hose from the servo to the rear elevator was cut, a spring mechanism snapped down the elevators and the V1 dropped to earth.
Compare this system with the Kettering Bug of WW1.
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You can get away with this approach if you don't give it too little or too many blips, which is one thing that took the German designers time and experimentation to refine. This sort of control system is quite common among missiles today. In WW2 strategy, the V-1 and V-2 were irrelevant. In the context of WW3, such machines, tipped with nuclear warheads, could be everything.
There are two shades to the Nuclear missile. The first, relevant only to the peculiar geographical situation of the US and USSR, is the Fractional Orbital Ballistic System, hereinafter known as FOBS. Because US and USSR are both northern hemisphere continents, either can dispatch a quick missile over the North Pole to the other. Such a vehicle does not enter an orbit, given that the word orbit implies a complete rotation around another body, but the trajectory follows orbital parameters for a short period.
The first American defensive radar network, the Distant Early Warning (DEW) line, was built across Arctic Canada, in defence against such a threat. As the dialogue of Mutual Assured Destruction ( MAD!) grew, FOBS matured into orbital weapons busses which had the capacity for Multiple Independent Reentry Vehicles( MIRV's). MIRV's included decoys, and some of the warheads had the ability for evasive manoeuvres.
This is a somewhat specialised area in unmanned vehicle technology. Operations in space, with the extreme velocities attendant for satellites, and the problems of re-entry, are rarely translatable to atmospheric situations.
Little had happened after WWII in the unmanned aircraft field. No-one saw any benefits in such technology, although the development of reconnaissance satellites did show a way, not that anyone saw any career potential in following it. Strangely enough, the USAF did develop what must have been a fairly sophisticed system for drone control of aircraft. Missile testing required targets. Usually, one saw a photo of some new missile demolishing an old airframe (typically a B-17). Careful attention to these photos disclosed that the old airframes also included such modern interceptors as the Convair F-106 - publicity blurbs usually refering to a QF-106. The Q prefix became known as a drone aircraft prefix.
The USAF was careful to use airframes noted for stability; in general, those designed for night interception, although the F-86 Sabre,almost a model of the well designed, stable airframe, was widely used initially. As even QF-86's were expensive, lower-cost vehicles were procured. High on the list here were vehicles such as the Ryan Firebee, developed as a Naval AA target drone ( the USAF did not have any anti-aircraft guns. But the US Navy still has quite a lot !). Hot rods such as the F-104 did not get a guersney, although a version of the mighty SR-71 Blackbird, which cruised at Mach 3, was intended to carry and launch a supersonic drone missile.
The technical system for controlling these target aircraft became fairly well developed and well known. In fact, there is no good reason why it could not have been developed into a tactical drone system.
When the anti aircraft gunnery system in North Viet Nam became extremely effective against reconnaissance aircraft, senior people looked around for some way to carry our pre and post strike recon without losing pilots. You want to look at the recon losses in Viet Nam, start with the USAF RF - 101 Voodoos based at Tan Son Nhut from about 1965. The Voodoo was quite a bit faster than the Phantom; yet the losses were significant.
Don't forget to include the Navy birds from Task Force 77, also from about 65. Some of these were RA - 5C Vigilantes - faster than the Voodoos, but some still failed to return. In the end, the photos were not worth the pilots, but target intelligence was still needed. So the Ryan Firebees - BQM - 134s, were pressed into service. The Firebees did not have the range to get into North Viet Nam from South Viet Nam so they were configured to be dropped from the venerable C-130. And, as they did not have the range to get out of North Viet Nam, the Herc was configured to collect them in mid air. The occassional C-130 with steel booms folded back from the nose which can still be seen at bases scattered around the globe, is, among other things, configured to recover Firebees using Fulton recovery gear.
The C-130 carried four Firebees on it's wing stations. The Herc loaded the drones, flew to a known point off the coast of North Viet Nam, from which the drones' navigation program could assume control. The writer does not know how the Herc and the Firebee synchronised this point back in those days, but it's possible that some Hercs were equiped with inertial nav systems adapted from ballistic missiles.
The Firebees' flight profile was loaded in software on board the drone. This means that some unfortunate person had to generate a machine language program, to be taped, which was read by the internal computer in the Firebee. This process often exhibited errors - machine and human. Instead of overflying at 2000 feet, one drone streaked down the main runway of the North Vietnamese fighter base at Kep at 200 feet, sending increduluous Vietnamese ( and probably the odd Russian advisor) scampering for their Migs. Most drones came back, but, with the bloody-mindedness peculiar to machines, some persisted in dropping into the sea instead of deploying their parachutes. The longest lived Firebee, Tom Cat, survived several hundred missions.
As well as simply ducking around and clicking its camera shutters, the Firebees achieved a magnificent tactical intelligence scoop. The main AA missile used by the North Vietnamese was the Russian SA - 2 Gainful. The SA - 2 is quite large, usually referred to by pilots as a firefarting telegraph pole. While various exercises in Europe had given the Americans the radar frequencies for the acquisition and targeting radars, no-one outside Russia knew the radar proximity fuse frequency. Yet this frequency was soon to be considered vital to countering the missile. There were so many missile radars in North Viet Nam that often the aircraft jammers were simply outnumbered, and the North Vietnamese seemed to be able to target missiles from one of several radars ( Read : Not in the USAF How To Do It Book).
A Firebee, suitably decorated to look like a Real Aeroplane, attracted and survived an SA - 2 missile detonation, getting the proximity fuse frequency at the same time. If you want to see this info being used, check " On Yankee Station", by Cmdr John B Nicholls, page 96. I quote:
"...glimpsed a missile emerging from the murk and wracked his aircraft into an evasive turn - then he saw two more in close trail headed for him. ……two frames of movie film showed the SAMs close aboard, passing narrowly in front of the F-4….The Prowlers had monitored 20 SAMs in the air at that time - too many to jam tracking or guidance frequencies. So the ECM operators had switched their attention to the detonation frequencies."
For quite obvious reasons, one sees little of this in the media. One of the big bogeys for the Allies in WWII was the German appreciation of, and thus development of a counter for, the radar proximity fuse for common ground to ground artillery.
When the war in Viet Nam wound down the fighter boys forgot about the drones. So did everyone else, except for a small air force in the middle east. They had some new ideas….
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Part Two: Drones First Strike |
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